Sensitized paper development device



Sheet of '4.

May 6, 1969 TOSHIO ISHIKAWA E A SENSITIZED PAPER DEVELOPMENT DEVICEFiled May 16, 196'? Fig a m b. UV. c w m m 6 d V d m M .w 6 m C m. I 3 0D 2 I .m d V m m g C 9 b .l m F C n F b b O 0 ll EEEwQEE. Al D C BA I?220595 62m Development velocity y 5, 1969 TOSHIO ISHIKAWA ET AL3,442,589 Y SENSITIZ ED PAPER DEVELOPMENT DEVICE Filed May 16, 1967Sheet 2 of 4 Fig4 Temperature -Developmem velocity Fig 5 6, 1969 TOSHIOlsHlKAwA ET AL- 3,442,589

SENSI'IIZED PAPER DEVELOPMENT DEVICE Filed May 16, 1967 sheet 3 of 4 i3T- I i FIG.6

I; 26 23 Q] 37i i Exposed Q- Sens/rive Paper Original POP! Sens/livePaper M y 6, 1969 TOSHIO ISHIKAWA ET AL 3,442,589

SENSITIZED PAPER DEVELOPMENT DEVICE Filed May 16, 1967 Sheet 4 of 4 FIG. 9

475 K 465 W 455 A ,4 J M United States Patent U.S. Cl. 355-'106 5 ClaimsABSTRACT OF THE DISCLOSURE An apparatus for heat development of positivesensitized paper which exposes sensitized paper first to a light sourceand then to a heat source. An electric curcuit in the devicesimultaneously controls both the velocity of the paper moving past bothsources and the developing temperature.

Related applications This application is a continuation-in-part ofapplication Ser. No. 399,784, filed Sept. 28, 1964.

Background The invention relates to copiers, and more specifically, tolight exposure and heat developer copiers having velocity andtemperature control circuitry.

temperature by compensating for any temperature changes due to heatabsorbed by the sensitized paper during development. The velocity of thepaper moving past the heat source is usually controlled by a motordriving a belt which carries the paper around the heating source. Boththe temperature and the development velocity must be considered so thatthe heat quantity necessary for sensitized paper is radiated uniformlyover the 7 paper surface.

Since it is generally desirable that he quantity of heat generatedorithe paper surface be approximately constant during development theratio of the development temperature and the paper velocity past theheat source, should also be approximately constant. If the operatingtemperature is changed to a higher level the velocity should beincreased correspondingly, or if the temperature is lowered the velocityshould be lowered.

In addition to maintaining an optimum relation between the temperatureand the velocity of paper movement in the development stage, it isdesirable in positive printing machines to synchronize the velocity ofthe sheet of paper moving through the light exposure stage with that ofthe developing stage. When synchronization between the stages is notmaintained, a portion of the paper inserted in both of the stagesbecomes either stretched or damaged; when the development stage velocityexceeds the light exposure stage or when the developing velocity fallsbelow that of the light exposure stage, a back up of light sensitizedpaper occurs causing stagnation of the paper prior to the developmentstage. Finally, it is necessary to provide some flexibility intemperature range set- 3,442,589 Patented May 6, 1969 tings of thedeveloper in order satisfactorily to develop prints from differentshades of original paper.

In the past positive printing developers have not been entirelysatisfactory in maintaining optimum heating characteristics when etherthe velocity ofthe sheet or the developer temperature was changed to anydegree-These devices also have failed to synchronize the paper sheettransportation rate through both the light exposure and heat developingstages and have experienced difiiculties in compensating for heat lossesin the development stage due to the removal of heat by the sensitizedpaper.

It is an object therefore to overcome the foregoing limitations anddifiiculties by providing anovel copier apparatus.

' Summary A novel copier for positive print developing is obtained bythe provision of a novel developer temperature and sheet velocitycontrol circuit in combination with a light exposure device and a heatdeveloper device. With the copier of this invention, it is possible toadjust development velocity to varying temperature ranges in accordancewith the shade of color of the original paper while the exposurevelocity is maintained constantly synchronized with the developingvelocity. Heat development efiiciency is maximized with an automaticadjusting control circuit which varies both the heat source temperatureand the sheet velocity simultaneously, thus providing a continuoustemperature velocity relationship.

Brief description of the drawings FIGS. 1-4 are graphs showingrelationships between the temperature and velocity of development;

FIG. 5 is a circuit diagram illustrating a control circuit of theinvention;

FIG. 6 illustartes light exposure and heat developing stages of a copierin accordance with the invention;

. FIG. 8.

Description 0f the preferred embodiments Referring now to the drawings,the graphs of FIGS. 1-4 shows the manner in which the temperature andthe developing velocity may be related. Normally when the velocity ofmovement of the developing portion of a copier becomes higher, .thetemperature should be higher and as it becomes lower the temperatureshould be lower. Sensitized paper becomes scorched below a, and thedevelopment is incomplete above a. Each corresponding velocity may havesome tolerance, such as M, b-b, etc. in FIG. 1, and may overlap to acertain degree as temperature is increased A, B, C, D. If, as in FIG. 2,satisfactory developing velocities do not overlap with increases intemperature, a gap n-m in the developing section could result if optimumoperating out by two stopping rollers 18 and 19. Both the original paperand light sensitized paper are combined together and inserted in thedirection of the arrow between the belt; which is-revolved by driving-roller'12 and-the periphery of cylinder 20.

The developing stage 26 has a heating roller 31 which rotates around aheating source 30. The heating source may be, for example, a heatingwire such as a Nichrome wire, or an infrared ray lamp. A belt 36 iswound around rollers 32, 33, 34 and 35 for carrying light-sensitizedpaper aroundthe heating roller. A heat insulatingmaterial 37 covers therollers 32-35 and belt and shields the heating roller 31. Whenlight-sensitized paper, which has been exposed in the light exposurestage, is inserted between the heating roller 31and the belt 36, it isdeveloped while the paper is revolved around the periphery of roller 31.Thelight exposure and-developing stages are shown being driven byythesame chain or belt linkage 22 from a gear 23 which may be-connected tothe drive shaft of t a motor- 9 (FIG. The rotation of the linkage 22rotates both. gear 25 on the developing section and gear 24 in theexposure section.

As-well known in the art, the. phase relation between the inputand'output voltages. of an AC bridge is reversed as one or more branchimpedances of the bridge are varied from one side-of the 'balance pointof the bridge to the opposite side thereof. Accordingly, it is possibleto form an AC bridge circuit consisting of an arm including a thermistorlocated at a desired temperature measuring point and the remaining threearms each including a resistor, so that for a given constant inputvoltage to the AC bridge, the polarity of the phase angle of the outputvoltage therefrom can be changed depending on whether the temperature ofthe thermistor is in excess of or is less than a certain preselectedvalue, which value is determined as a function of thetemperatureresistance characteristics of the thermistor and resistancevalues of resistors of the three arms of the bridge. With the provisionsof a phase discriminator circuit to check the polarity of the phaseangle of the output voltage from the bridge and an electric heaterconnected to the phase discriminator circuit, then it is possible toswitch on and switch off the heater in response to each change-over ofthe polarity of the phase angle of the output voltage of the bridge andhence in response to the temperature variation of the thermistor passinga certain preselected value determined by the design of the bridge.

In FIG. 5, the circuit includes a thermistor 1 in a bridge leg,resistance leg 2 having a plurality of temperature setting contacts F,G, H being separately switched into a bridge circuit 3 that is connectedto AC amplifiers 4 and S which are in turn connected to a phasediscriminator 6 that controls operation of a relay a power transformer11 is the power source for the circuit and 'the temperature settingcontacts F, G, H are interconnected with speed control means 7 and 8 forthe motor 9.

In the particular embodiment of the AC bridge shown in FIG. 5, one armconsists of the thermistor 1 located at a desired temperature measuringpoint and another arm is adapted to be selectively connected to one ofthe resistors in resistance leg 2 for facilitating the temperaturesetting, while the remaining two arms consist of resistors R and R ofidentical resistance values connected by a variable resistance R foradjustment. The AC amplifiers 4, S consist of PNP type transistors 4Tand ST, respectively, and the phase discriminator circuit 6 is also madeof a PNP type transistor 6T. The coil L1 of relay 10 is connected to thetransistor of the phase discriminator circuit 6 as a collector loadthereof, so that the relay 10 is energized when the transistor isconductive, and the relay contact is closed. The relay contact is keptopen as long as the transistor of the discriminator circuit 6 isnonconductive.

The power source transformer 11 is provided to apply a half-wayrectified voltage across the collector and the emitter of the transistor6T through suitable diodes. As far as direct voltage is concerned, theemitter and the base of the transistor'of the circuit 6 are at the samepoential.

A collectorcur-rent flows through-the relay 10 if the emitter is madepositive with respect to the base of the transistor 6T during the periodwhen the emitter is kept positive with respect to the collector, namely,during the positive half cycle of the power source voltage. If an ACvoltage applied acrossbthe emitter and the base of the transistor 6T' inthe aforesaid phase relation with the power source voltage, then thecollector current flows during each positive half cycle of the powersource voltage. On the other hand, if the AC voltage across the emit.-ter and the base of the transistor 6T is so phased as to keep theemitter negative with respect to the base during the positive half cycleof the power source voltage, then the transistor is'kept nonconductiveand'the'relay 10 is not actuated. v

In FIG. 5, the temperature and velocity control circuit is used tocontinuously control sheet velocity and heat developer temperature in acopier such as that illustrated in FIG. 6. A predetermined temperaturesetting is first made at resistor 2 with one or more contacts F, G, Hbeingswitched into the bridge circuit. 'At the same time, the variablespeed control transformer 8 has appropriatetaps f, g, h, etc. connectedto a full wave rectifier comprising diodes D D D and D Under optimumdeveloping conditions bridge 3, comprising resistors R R R thermistor 1and variable selection resistors 2, is balanced. 'Ihermistor 1 islocated in the vicinity of the heat-development roller and detects anychanges in temperature. If the bridge becomes unbalanced, a signalis'pickedup at variable resistor R and is transmitted through capacitorC to the amplifier 4. The signal passing through capacitor C goesthrough a voltage divider and resistor R connected to the base oftransistor 4T. The voltage dividing circuit consisting of and RC networkR C and a resistor R is connected between capacitor C and resistor R Theamplifier transistor 4T has a resistor R and capacitor C connected inparallel between the emitter and junction A of the bridge network. Theamplifier transistor 4T has a DC current path through resistor Rresistor R and diode D to winding L of transformer 11.

, An AC path exists through capacitor C voltage divider networkcomprising resistors R R and resistor R to the base of transistor ST. Acurrent limiting diode D is connected between the base and emitterelectrodes of transistor 5T. An output signal from the collector oftransistor ST is coupled through RC network C and R to the base of relaytransistor 6T. When transistor 61 has a collector output signal throughinductor L and capacitor C relay 10 is actuated in order to control theamount of heating current to be applied to the heating source.

The output circuit of transistor 6T is completed through diode D andwinding L A capacitor C is connected in a conductor extending from ajunction 38 between the bridge legs 1 and 2 and a junction betweenresistors R and R Winding L is connected between two junctions of thebridge circuit and the primary winding L, of transformer 11 is connectedto a suitable power source.

The transformer 8 includes a primary winding L connected to a suitablepower source and a secondary winding L providing variable speed controlto motor 9 through the full wave rectifier consisting of diodesD D D andD A motor coil L provides feedback signals through a full wave rectifierconsisting of diodes D D D and D for a DC control signal through windingL to insure synchronization of motor 9 at the desired speed. The threetransformer taps f, g and h are separately switched to a junction 39which is connected to the junction between diodes D and D If it isassumed in FIG. 5 that the two secondary windings L and L of the powersource transformer 11' are so connected that corresponding ends aresimultaneously made positive with respect to the opposite ends thereof,and if it is further assumed that the variableresistor R for adjustmentisset at the center point thereof and the resistance of the thermistor 1is higher than the particular resistance 2 selected at the particularmoment,

which means that the temperature of the thermistor lo cated at thedesired measuring point is lower than a preselected temperature settingmade on the resistor 2, then the output voltage from the bridge 3 isapplied to the transistor 4T across the emitter and the base thereof insuch polarity that the emitter is kept positive with respect to the baseduring the positive half cycle of the power source voltage applied tothe transistor 6T, namely, that half cycle when the emitter of thetransistor 6T is kept positive with respect to the collector of thesame. Since the power source voltage to the amplifier circuits 4 and 5is half-wave rectified by diodes and then applied thereto through filtercircuits consisting of resistors and capacitors, the transistors 4T andST of the amplifier circuits are made conductive under such conditionsthroughout each cycle. Thus, the output voltage from the bridge circuit3, which is applied to the amplifier circuit 4, is amplified by the ACamplifier circuits 4 and 5, and then applied to the phase discriminatorcircuit 6. Due to the fact that the output and input voltages are inphase in the case of a two-stage AC amplifier of resistor-capacitorcoupling type as shown in FIG. 5, the output voltage of the bridgecircuit 3 is amplified and applied to the transistor 6T across theemitter and base thereof after being amplified without anyphase-shifting. Thus, as described above, in the transistor 6T, theemitter is'made positive with respect to the collector in synchronismwith the AC voltage making the emitter positive with respect to thebase. Thereby, the transistor 6T is made conductive to actuate the relay10 and the relay contact is closed. Upon closure of the relay contact,an electric heater in the developing portion is energized or switched onto heat up the developing portion.

As the temperature of the developing portion is raised by such heating,the temperature of the thermistor 1 located in a suitable measuring areaof the developing portion 26 is also increased, and accordingly, theresistance of the thermistor becomes lower. When the resistance of thethermistor is lowered to the same value as that of the resistor 2preselected for temperature setting, the bridge circuit 3 is balanced,and the output voltage from the bridge becomes zero. Thus, no voltage isapplied to the transistor 4T as an input voltage thereto, and thetransistor 6T becomes nonconductive to deenergize the relay 10.Consequently, the contact of the relay 10 is opened and the electricheater is switched off.

If there is a considerable time delay between the heating effect of theelectric heater and the temperature of the thermistor 1 in thedeveloping portion to cause temperature rise even after switching offthe heater, the resistance of the thermistor is excessively loweredbeyond the value for proper balance of the bridge circuit 3 to againunbalance the bridge. However, the output voltage from the bridgecircuit 3 under these conditions is produced in exactly opposite phaserelation to the power source voltage applied to the transistor 6T;namely, when the collector of the transistor 6T is made positive withrespect to the emitter by the power source voltage from the bridgecircuit 3. Thus, the transistor 6T is kept nonconductive.

With the electric heater switched off, the temperature of the developingportion 26 is gradually reduced to increase the resistance of thethermistor 1, and when the resistance value of the thermistor isincreased in excess of the aforesaid preselected resistor for setting,then the balance of the bridge circuit is again broken in the samemanner as described above. Thus, the transistor 6T of the discriminatorcircuit 6 is made conductive to energize the electric heater.

As a result of it, when the temperature of the thermistor is low and theresistance thereof is larger than that of a resistor 2 preselected fortemperature setting, the heater is switched on. On the other hand, whenthe temperature of the thermistor is high and the resistance thereof issmaller than that of the resistor for temperature setting, the heater isswitched off. By providing a plurality of different resistors havingsuitable resistance values for temperature settings, the temperaturesetting can be changed by selectively connecting one of such resistorsto the bridge circuit 3. By the operation of the variable resistor R foradjustment, the temperature setting can be made with fine adjustment.

Two embodiments which may be used to interconnect the temperaturecontrol circuit with the motor speed control are shown in FIGS. 7 and 8.In FIG. 7 changeover contact members 41 and 42 are spacedly mounted on aspindle 44 attached to a dial 43. The switching members 41 and 42 alwaysmake contact with junctions 38 and 39, respectively, but are switchablebetween contacts F, G, H, and f, g, h, respectively, so that any changein temperature setting makes a corresponding velocity change and viceversa.

With the dial 43 positioned as illustrated in FIG. 7, the secondary tapg of the transformer 8 is connected to the rectifier bridge through therotary member 41, and a direct voltage from the rectifier bridge isapplied to the armature of the DC motor 9. The other rotary member 42connects a temperature setting resistor G to the bridge circuit 3. Thus,the revolving speed of the motor 9 is determined by the voltageappearing on the secondary tap g of the transformer 8 thus selected, andthe temperature of the developing portion is regulated by thetemperature setting resistor 26 thus connected to the bridge 3.

When the dial 43 is rotated in a counterclockwise direction from theposition of FIG. 7, the revolving speed of the DC motor 9 is determinedby a secondary tap h of the transformers 8, while the temperature of thedeveloping portion is regulated by the temperature setting resistor 2H.Conversely, if the dial 43 is rotated in a clockwise direction from theposition of FIG. 7, the revolving speed of the motor 9 is determined bythe secondary tap f of the transformer 8, while the temperature of thedeveloping portion is regulated by the temperature setting resistor 2F.

FIG. 8 shows another example of setting device of the revolving speedand developing speed by means of microswitches and a variable singlewinding transformer, in which three earns 45, 46 and 47 are secured tothe dial shaft 44 so as to cooperate with microswitches 455, 465 and475, respectively. Also secured to the dial shaft is a rotary contactarm 42 of the variable single winding transformer 2VR. With the settingdial positioned as shown in FIG. 8, only the microswitch 475 isactuated. As the setting dial 43 is rotated in a counterclockwisedirection, the microswitches 465 and 475 are actuated successively, andfinally all the microswitches 455, 465 and 475 are actuatedsimultaneously. If the setting dial 43 is turned to the extreme end ofthe clockwise direction, all the microswitches 455, 465 and 475 areswitched off simultaneously. The rotation of the contact arm 42 of thevariable single winding transformer 2VR is so arranged that it is notpossible to transfer from the condition of simultaneous actuation of themicroswitches to the condition of the simultaneous switching-off of allmicroswitches and vice versa.

FIG. 9 illustrates four temperature range adjustments by means of fourresistors K, L, M and N and with corresponding changes in developmentvelocity. The temperature setting resistors to be connected to thebridge circuit 3 under each operative condition of the microswitches areshown in the following table.

TABLE Conditions Microswitch No. I

In the particular example shown-in FIG. 8, the combination of the camsand the microswitches can take only four positions designated byconditions I to IV in the table, and the microswitches are always in oneof the four conditions selected by suitable combinations of the cams 45,46 and 47. Thus, the revolving speed is regulated by the rotation of thecontact arm of the variable single winding transformer ZVR, and at thesame time the temperature setting of the developing portion can beswitched over in a very reliable manner.

What is claimed is:

1 1. In apparatus for heat development of positive sensitized sheets,the combination comprising, an exposure device having a light source andfirst means for moving an original copy and a sensitized sheetconjointly past said light source to expose said sensitized sheet; aheat development device. having a heat source and second means formoving the exposed sensitized sheet past said heat source to developsaid sheet; switch means selectively operable to connect said heatsource to a source of potential; a thermistor operatively associatedwith said heat development device and subjected to the temperaturetherein; an electric control circuit including an A.C. bridge, amplifiermeans connected to the output of said bridge and a phase discriminatorconnected to the output of said amplifier means, said thermistor beingconnected in an arm of said bridge; means applying a first A.C.potential to the input of said bridge and a second A.C. potential tosaid phase discriminator, said first and second A.C. potential being inphase coincidence; the amplified output potential of said A.C. bridgeconstituting a third A.C. potential which is applied to said phasediscriminator; said switch means being connected to said phasediscriminator and closed thereby when said second and third A.C.potentials are in substantial phase coincidence; the phase of said thirdA.C. potential, relative to that of said first and second A.C.potentials, being dependent on the resistance value of said thermistor;said third A.C. potential being substantially in phase with said secondA.C. potential when the resistance of said thermistor is above aselected value, and being in phase opposition with said second A.C.potential when the resistance of said thermistor is below said selectedvalue.

2. In apparatus for heat development of positive sensitized sheets, thecombination claimed in claim 1, including an adjustable resistance insaid bridge for setting said selected value; the output of said bridgebeing zero when the resistance of said thermistor is at said selectedvalue.

3. In apparatus for heat development of positive sensitized sheets, thecombination claimed in claim 1, in which said amplifier means comprisesan RC coupled two-stage amplifier.

4. In apparatus for heat development of positive sensitized sheets, thecombination claimed in claim 3, in which the stages of said amplifierscomprise transistors having said second A.C. potential applied to theiroutputs; said phase discriminator comprising a transistor having saidsecond A.C. potential applied to its collectoremitter circuit; saidswitch means comprising a switch operating coil in the collector circuitof the transistor of said phase discriminator; the output of said bridgebeing applied to the input of the transistor of the first stage of saidamplifier.

5. In. apparatus for heat development of positive sensitized sheets, thecombination claimed in claim 1, including plural resistors of respectivedifferent resistance values included in an arm of said bridge and eachhaving one terminal commonly connected to one input terminal of saidbridge; first selector switch means selectively operable to connect theother terminal of a selected one of said resistors to an output terminalof said bridge; an electric motor commonly driving said first and secondmeans; a source of potential having plural terminals at respectivediflFerent potentials; and second selector switch means selectivelyoperable to connect said motor to a selected one of the terminals ofsaid last-named source of potential; said first and second selectorswitch means being interconnected for conjoint operation to control thespeed of operation of said first and second means in ac cordance withthe resistance setting of said A.C. bridge.

References Cited UNITED STATES PATENTS 3,207,896 9/1965 Meaney -77.5X3,224,355 12/1965 Thomiszer 9577.5

JOHN M. HORAN, Primary Examiner.

US. Cl. X.R. 9589

